1. FIELD OF THE INVENTION
The invention relates to a track-adjusting wheel especially for tractors and the like, having a wheel dish arranged releasably and shiftably on retaining brackets of the rim, which retaining brackets are distributed over the inner periphery of the rim and are of approximately U-shaped cross-section, and have on their legs aligned bolt holes for axial screws serving for fastening the wheel dish, and outwardly directed flanges which lay against the rim base and with which the retaining brackets are connected to the rim by means of welding seams extending in the peripheral direction of the rim.
Track-adjusting wheels are used for adjusting the track on farming tractors and also on other vehicles for agricultural and forestry purposes Conventional trackadjusting wheels have wheel dishes which can be connected to the wheel rim in different axial adjustment positions by means of fastening screws. At the same time the rims are equipped with welded-on retaining brackets which are distributed over their inner periphery and to which the multi-lobed wheel dish is connected by means of the screws. With the known track-adjusting wheels, various track adjustment possibilities, generally eight track settings, are obtained from the particular position of the rim relative to the wheel dish or of the wheel dish relative to the wheel-hub flange. With a track jump of generally 1OO mm, the track of a tractor can therefore be varied over 700 mm.
2. DESCRIPTION OF THE PRIOR ART
Many designs for the retaining brackets serving for the screw fastening of the wheel dish have been proposed and used in the past, for instance U-shaped, angular or S-shaped retaining brackets of even so-called omega brackets. The known retaining brackets are connected to the rim by means of axial welding seams or by means of welding seams extending in the peripheral direction of the rim, but occasionally also by means of a combination of both welding seams (German Patent Specification 837,649, G.B. Patent Specification 666,112, German Patent Specification 2,247,007, German Utility Model 7,605,257 and European Patent Specification 0,025,677). In the past, however, there have also already been proposals to provide other types of connection, for example rivet or clamping connections, in order to connect the rim and the wheel dish. In one example of a known track-adjusting wheel, the rim is fixed to the wheel body by means of axial screws, eccentric bolts and clamping pieces along a continuous radial groove, or as a result of the pressing in of the rim base. Also, stop projections are arranged on the rim base in order to prevent rotation of the rim relative to the wheel body (U.S. Patent Specification 2,254,361).
It has also long been known to use for trackadjusting wheels and other wheels four-lobed wheel dishes which can be produced from square sheet metal blanks in a material-saving and therefore cost-effective way (French Patent Specification 871,754). On track-adjusting wheels, the screw fastening of the wheel dish to the rim is carried out at each of the four dish corners or dish lobes either by means of only a single fastening screw, or by means of a pair of screws, either single or double retaining brackets being provided at the fastening points (European Patent Specification 0,025,677).
Regardless of the many known designs of the retaining brackets, in the past these have always been welded to the rims in such a way that the axial and radial forces exerted on the wheel during use and the drive torque are transmitted via the connections of the welding seams. The extremely high wheel loads occurring during use and frequently acting as impact forces lead to considerable stresses and correspondingly pronounced deformation of the retaining brackets and consequently also to highly detrimental stresses being exerted on the welded joints, with the result that, under specific conditions of use of the tractors, the welding seams and/or the retaining brackets often break. A break of the welded joints cannot be reliably prevented by a reinforcement of the retaining brackets, which in any case involves an increased outlay in terms of production.